1. Field of the Invention
This invention relates generally to the transdermal delivery of medicament and, more specifically, to a wearable programmable apparatus for the iontophoretic and/or ionosonic delivery of medication across the skin or other biological tissue for the prevention of a disease such as thrombosis and the management and treatment of medical conditions such as substance abuse.
2. Reference to Copending Patent Application
Reference is made herein to copending application Ser. No. 08/044,586 filed Apr. 7, 1993 entitled: Ionosonic Drug Delivery Apparatus, now abandoned, by the present inventor.
3. Prior Art
Iontophoresis has existed for several centuries as a means for applying medication locally through a patient's skin and for delivering medicaments to the eyes and ears. The application of an electric field to the skin is known to greatly enhance the skin's permeability to various ionic agents. The use of iontophoretic techniques has obviated the need for hypodermic injection of certain medicaments, thereby eliminating the concomitant problems of trauma, pain and risk of infection to the patient.
Iontophoresis involves the application of an electromotive force to drive or repel oppositely charged ions through the dermal layers into the area to be treated; either into the surrounding tissues for localized treatment or into the circulatory system for systemic treatment. Positively charged ions are driven into the skin at the anode while negatively charged ions are driven into the skin at the cathode. Studies have shown increased skin penetration of drugs at anodic or cathodic electrodes regardless of the predominant molecular ionic charge. This effect is mediated by polarization and osmotic effects. Regardless of the electrical charge on the medicament employed, two electrodes are used in conjunction with the patient's skin to form a closed circuit to promote the penetration or absorption of the medicament through the skin underlying the working electrode.
One readily observed benefit of transdermal iontophoretic drug delivery is the increased efficacy of the drugs delivered in this fashion. U.S. Pat. No. 5,160,316, to the instant inventor, incorporated herein by reference, describes the use of a multichannel dispersive electrode. Each channel is driven by separate electronic circuits to assure wide dispersion and enhanced penetration of medicament. Such wide field electrodes not only can cover a wide area of body without succumbing to "tunneling effects" but provide sufficient skin penetration to function as a systemic drug delivery system. A co-pending patent application by the present inventor describes a user-friendly iontophoretic system to deliver nicotine as a means for helping people quit smoking or, alternatively, to provide established smokers with a noncarcinogenic smokeless cigarette. Another co-pending patent application describes the novel utilization of an integrated system of multichannel iontophoretic drivers combined with ultrasonic piezoelectric elements to achieve greater skin penetration of transdermal deliverable drugs and even larger peptide molecules such as insulin.
Transdermal delivery of medicament offers a new and potentially powerful tool for the treatment of substance abuse and dependency problems. Substance abuse/dependency has in recent years emerged as a significant problem for our society, not to mention the suffering and health of substance-dependent individuals and their families who are substance dependent. Substances that are commonly abused and constitute a significant costly impact on our society are; FOOD, TOBACCO, ALCOHOL, AND DRUGS. Although substance dependency is a complex and multifactorial entity beyond the scope of this discussion, recent studies have identified some common factors. Each substance abuse situation creates an altered mental state, and temporarily satisfies an inner need. Many substance dependent people desire and struggle to be free of their dependency.
Current treatments employ a combination of supportive social and psychological treatment in conjunction with pharmacological intervention that either blocks the effect of, or substitutes for, the substance being abused. Pharmacological intervention has shown itself to be of increasing value in the management of substance abuse. Studies are identifying drugs and peptides which are active in appetite suppression for weight loss treatment. Studies are showing increasing efficacy of medications in the detoxification and perhaps ultimate treatment of drug dependency. Current management has been limited by patient compliance and difficulties associated with outpatient management of substance abusers.
In view of the foregoing problems with current management and treatment regimens, it is desirable to provide a method for helping a patient conquer his/her addiction while allowing the patient to exercise significant control over their own treatment. An intelligent, programmable transcutaneous drug delivery system that is portable, can be worn for extended periods of time, can be dose limited, deliver a substance that blocks or substitutes for the dependency in a pre-programmed manner, and can deliver additional medication rapidly under patient control for special situations of greater need, would provide a powerful adjunct to the management of people who are substance dependent.